Sealed primary sodium-halogen cell

ABSTRACT

A sealed primary sodium-halogen cell is disclosed which comprises a casing, an anode positioned in the casing, the anode selected from the class consisting of sodium, sodium as an amalgam, and sodium in a nonaqueous electrolyte, a solid sodium ion-conductive electrolyte positioned in the casing adjacent the anode, and a cathode positioned adjacent the opposite side of the electrolyte, the cathode comprising sulfuryl chloride, sulfuryl chloride with aluminum chloride, or sulfuryl chloride with ferric chloride.

451 Apr. 22, 1975 3.8l7 790 6/1974 l36/83 R l l SEALED PRIMARY SODIUM-HALOGEN CELL [75] Inventors: Gregory C. Farrington, Clifton 'f 'f Williams Park; pew. C. Lord, Schenectady ASSISldIlI l'..\'ammerC. F. LeFevour both of Attorney, Agent. or Firm-Paul R. Webb II; Joseph T. Cohen; Jerome C. Squillaro [73] Assignee: General Electric Company,

Schenectady. NY.

Apr. 5, 1974 [57] ABSTRACT A sealed primary sodium-halogen cell is disclosed which comprises a casing, an anode positioned in the casing, the anode selected from the class consisting of sodium, sodium as an amalgam, and sodium in a non- [22] Filed:

Appl. No.: 458,092

aqueous electrolyte, a solid sodium ion-conductive electrolyte positioned in the casing adjacent the anode, and a cathode positioned adjacent the opposite side of the electrolyte, the cathode comprising sulfuryl chloride, sulfuryl chloride with aluminum chloride, or sulfuryl chloride with ferric chloride.

References Cited UNITED STATES PATENTS 3,793,080 136/83 R 2 Claims 1 Drawing Figure SEALED PRIMARY SODIUM-HALOGEN CELL This invention relates to sealed primary sodiumhalogen cells and, more particularly. to such cells employing a cathode of sulfuryl chloride, sulfuryl chloride with aluminum chloride, or sulfuryl chloride with ferric chloride.

Sodium-halogen cells are known in the prior art as. for example, described in Hess US. Pat. No. 3,793,080 issued Feb. 19, 1974 under the title Sealed Primary Sodium-Halogen Battery With Bromine-lodine Mixture." This patent describes and claims such a battery in which the cathode comprises a mixture of bromine and from 5.0 to 60 weight percent of iodine with specific conductive material, additives or both. The subject patent is assigned to the same assignee as the present application.

An article entitled "Lithium Anode Cells Operating at Room Temperature in Inorganic Electrolytic Solutions by James J. Auborn, et a]., appeared on pages l,6l3-l,6l9 of the Journal of the Electrochemical Society, Vol. 120, No. 12, December, 1973. A study of such cells is reported in the next article in the above Journal volume entitled Lithium Inorganic Electrolyte Cells Utilizing Solvent Reduction" by Wishvender K. Behl, et al., at pages l,6l9-1,623. Thus. a description of the first article would appear to be sufficient to describe the cells therein.

ln the above first article, there is described a first cell structure which has a solid cathode of active material, such as CuF- or W carbon powder, and a binder on a nickel screen. The cathode is sealed in a nonwoven polypropylene envelope and positioned within a lithium anode folded to envelope the cathode on both sides. The lithium anode consists of a nickel screen pressed into a lithium foil. This structure is placed in a rectangular polyethylene jar. An electrolyte is added to complete the cell. The electrolyte consists of a solvent and a solute. The solvent is selected from phosphoryl chloride, POClg, sulfuryl chloride. SO CI or thionyl chloride, SOCl The solute consists of AlCl AlBr or LiAlBr A second cell structure is described wherein the arrangement of the elements is similar to the arrangement in the first cell structure. The anode is identical and the woven separator is identical. The electrolyte has the same solvent and solute as the first cell structure. However, it additionally contains a reactant of chlorine or bromine. The cathode has a carbon, platinum or nickel current collector. The reactant for the cathode comprises the chlorine or bromine contained in the electrolyte.

In copending patent application Ser. No. 458,089, filed Apr. 5, 1974, in the names of Gregory C. Earrington and Peter C. Lord entitled Sealed Primary Sodium-Halogen Cell, there is described and claimed such a cell wherein the cathode comprises thionyl chloride, or thionyl chloride with various other compounds. This copending application is assigned to the same assignee as the present application.

As opposed to the cell configurations as described in the above first article and the tests described in the above second article, the present invention relates to a primary sodium-halogen cell which has a substantially different structure. The present invention is a sealed cell. Secondly, the anode is selected from the class of sodium, sodium as an amalgam and sodium in a nonaqueous electrolyte. Thirdly. the present invention has an electrolyte of a solid sodium ion-conductive material as opposed to the liquid electrolyte of the abovedescribed cell constructions. Fourthly, the cathode of the present invention comprises sulfuryl chloride, sulfuryl chloride with aluminum chloride, or sulfuryl chloride with ferric chloride.

In the above described cells, the electrolyte is in contact with both the cathode and the anode. The cathode is surrounded merely by a porous nonwoven envelope. Thus, the sealed primary sodium-halogen cell of the present application is substantially different from the above-described cells. Furthermore, in the above second cell configuration the electrolyte contains chlorine or bromine which liquid reactant comprises the cathode. Since the chlorine or bromine is in contact with both the anode and cathode there results a high rate of self-discharge due to the chlorine or bromine dissolved in the electrolyte. Further, there is a chemical interaction with the lithium anode to form the respective lithium bromide or lithium chloride salt. While some of this salt dissolves, more of this salt forms a solid precipitate in the cell.

The primary object of our invention is to provide a sealed primary cell which has a near zero self-discharge rate, high cell voltage and high energy density.

In accordance with one aspect of our invention, a sealed primary sodium-halogen battery comprises a casing, an anode positioned in the casing, the anode selected from the class consisting of sodium, sodium as an amalgam, and sodium in a nonaqueous electrolyte, a solid sodium ion-conductive electrolyte positioned in the casing adjacent the anode, and a cathode positioned adjacent the opposite side of the electrolyte, the cathode only comprising sulfuryl chloride, SO Cl sulfuryl chloride with aluminum chloride, or sulfuryl chloride with ferric chloride.

These and various other objects, features and advantages of the invention will be better understood from the following advantages taken in connection with the accompanying drawing in which:

The single FIGURE is a sectional view of a cell made in accordance with our invention.

In the single FIGURE of the drawing, there is shown generally at 10 a sealed primary sodium-halogen cell embodying our invention which has a metallic casing 11 including an anode portion 12 and a cathode portion 13. An anode 14 of sodium as an amalgam is shown positioned within anode portion 12. A cathode 15 comprising a saturated solution of aluminum chloride in sulfuryl chloride, SO CI is positioned only within cathode portion 13. A solid sodium ionconductive electrolyte 16 is positioned between and adjacent anode l4 and cathode 15. Electrical leads (not shown) are affixed to the respective casing portions. Closed fill tubes 17 and 18 are associated with the respective portions 12 and 13. Electrolyte 16 is secured on opposite sides to portions 12 and 13 by identi' cal glass seals 19.

A sealed primary sodium-halogen battery is formed by providing a metallic casing, providing an anode within the casing, the anode selected from the class consistingof sodium, sodium as an amalgam, and sodium in a nonaqueous electrolyte, providing a solid sodium ion-conductive electrolyte adjacent the anode. and providing a cathode adjacent the opposite side of the electrolyte, the cathode only comprising a liquid selected from the class consisting of sulfuryl chloride, sulfuryl chloride with aluminum chloride, or sulfuryl chloride with ferric chloride. We found that such cells have open circuit voltages of 4.4 volts.

The anode may consist of sodium, a sodium amalgam or sodium in a nonaqueous electrolyte. The sodium amalgam can be in the range of compositions from about 95% sodium and 5% mercury by weight to about 35% sodium and 65% mercury. For the fully charged state of the cell, the amalgam composition is preferably high in sodium. Cells using sodium amalgams cannot be used efficiently at temperatures below 2l.5C due to complete freezing of the amalgam.

The use of nonaqueous electrolytes permits cell operation to much lower temperatures as determined by the freezing point of the electrolyte. A preferred electrolyte is propylene carbonate in which a sodium halide salt is dissolved. This electrolyte permits cell operation down to O.C.

We found unexpectedly that a suitable cathode for a sealed primary sodium-halogen cell with a sodium reactant anode and a solid ion-conductive electrolyte is sulfuryl chloride, SO Cl sulfuryl chloride with aluminum chloride, or sulfuryl chloride with ferric chloride. We found that sulfuryl chloride combines several properties most desirable for this type of cell. Sulfuryl chloride is stable, and reasonably conductive when aluminum chloride is added. Sulfuryl chloride is an oxidizing agent rivaling chlorine. The preferred cathode is a saturated solution of aluminum chloride in sulfuryl chloride.

We tried sulfuryl chloride alone and with several other materials in attempts to find a desirable cathode for the above type of cell. Other materials, which were tried with the sulfuryl chloride, were thionyl chloride and tetraethylammonium chloride. The most desirable cathode material developed to be a solution of sulfuryl chloride and aluminum chloride. A saturated solution of aluminum chloride in sulfuryl chloride was preferred because it was quite conductive. This solution is contained only within the cathode portion of the cell and is separated from the anode by the solid sodium ionconductive electrolyte. There is no sulfuryl chloride in the anode portion of the cell.

The anode casing portion can be made of nickel, Kovar alloy, niobium or tantalum, while the cathode casing portion should preferably be niobium or tantalum. These metals have been shown to be chemically stable in their respective environments.

A method of hermetically sealing the anode and cathode portions of the casing to opposite sides of the solid electrolyte is described and claimed in copending patent application Ser. No. 148,793, filed June I, 1971, under the title Method of Forming a Metallic Battery Casing in the name of Stephan P. Mitoff. This copending application is assigned to the same assignee as the present application.

In the above method, a disc of solid sodium ionconductive electrolyte, for example, sodium betaalumina, has stacked thereon a ring of General Electric Company 1013 glass cut from tubing. The glass ring has approximately the inside and outside diameter of the cup lip of easing portion. On the glass ring is stacked the nickel anode portion in cup form with its lip adjacent the ring. The three components are positioned on a supporting jig and lowered into an inert atmosphere furnace at 1,000C for about 1 minute. The resulting seal is helium leak-tight. The process is repeated to sea] the cathode portion to the opposite surface of the solid electrolyte. Both anode and cathode portions can also be sealed simultaneously to the disc in the above manner.

The anode portion can be filled with sodium, sodium as an amalgam, or sodium in a nonaqueous electrolyte through tube 17 after which the tube is sealed, as for example, by welding. The cathode portion is filled with a solution of sulfuryl chloride and aluminum chloride through tube 18, after which the tube is similarly sealed. The resulting device is a sealed, primary sodium-halogen cell. Leads (not shown) are attached to the respective casing portions for operation of the cell.

Examples of primary sodium-halogen cells made in accordance with our invention are set forth below:

EXAMPLE 1 A sealed primary sodium-halogen cell was constructed which employed an outer metallic casing with an inner tubular vessel or casing of solid sodium betaalumina as the electrolyte. The inner vessel formed the anode portion while the surrounding casing, spaced 'apart from the anode, formed the cathode portion. The

anode portion was filled with a sodium amalgam of a composition of weight percent of sodium and 10 weight percent of mercury as the anode. A saturated solution of aluminum chloride in sulfuryl chloride, approximately 0.5 molar, was added only to the cathode portion as the cathode. The resulting device was a sealed primary sodium-halogen cell. An open circuit voltage of 4.4 volts was obtained.

EXAMPLE 2 The cell of Example 1 exhibited at 25C the following polarization behavior which is shown below in Table I.

TABLE 1 Voltage- Current Density- Volts p: cm

EXAMPLE 3 The cell of Example 1 was discharged at a current density of 0.1 ma/cm for 450 hours.

While other modifications of the invention and variations thereof which may be employed within the scope of the invention have not been described, the invention is intended to include such as may be embraced within the following claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. A sealed primary sodium-halogen cell comprising a casing, an anode positioned in the casing, the anode selected from the class consisting of sodium, sodium as an amalgam, and sodium in a nonaqueous electrolyte, a solid sodium beta-alumina ion-conductive electrolyte positioned in the casing adjacent the anode, and a cathode positioned adjacent the opposite side of the electrolyte, the cathode only comprising a liquid selected from the class consisting of sulfuryl chloride, sulfuryl chloride with aluminum chloride, and sulfuryl chloride with ferric chloride.

2. A sealed primary sodium-halogen cell as in claim 1, in which the cathode comprises a saturated solution of aluminum chloride in sulfuryl chloride. 

1. A SEALED PRIMARY SODIUM-HALOGEN CELL COMPRISING A CAS ING, AN ANODE POSITIONED IN THE CASING, THE ANODE SELECTED FROM THE CLASS CONSISTING OF SODIUM, SODIUM AS AN AMALGAM, AND SODIUM IN A NONAQUEOUS ELECTROLYTE, A SOLID SODIUM BETAALUMINA ION-CONDUCTIVE ELECTROLYTE POSITIONED IN THE CASING ADJACENT THE ANODE, AND A CATHODE POSITIONED ADJACENT THE OPPOSITE SIDE OF THE ELECTROLYTE, THE CATHODE ONLY COMPRISING A LIQUID SELECTED FROM THE CLASS CONSISTING OF SULFURYL CLORIDE SULFURY CHLORIDE WITH ALUMINUM CHLORIDE AND SULFURYL CHLORIDE WITH FERRIC CHLORIDE.
 1. A sealed primary sodium-halogen cell comprising a casing, an anode positioned in the casing, the anode selected from the class consisting of sodium, sodium as an amalgam, and sodium in a nonaqueous electrolyte, a solid sodium beta-alumina ion-conductive electrolyte positioned in the casing adjacent the anode, and a cathode positioned adjacent the opposite side of the electrolyte, the cathode only comprising a liquid selected from the class consisting of sulfuryl chloride, sulfuryl chloride with aluminum chloride, and sulfuryl chloride with ferric chloride. 